Automatic trunk-selector.



A. M; BUL'LABD. AUTOMATIC TRUN K SELECTOR. APPLICATION FILED SEPT. 10. 1905.

1,-191152. Patented July 18, 1916.

' UNITED STATES PATENT OFFICE.

,ALBERT m. RUL'LARD, on NEW YoRx, N. Y. I

INCORPORATED, A CORPORATION on NEW YORK. Q

WESTERN ELECTRIC COMPANY,

, ASSIGNOR,

BY MESNE ASSIGNMENTS, TO-

AUTOMATIC TRUNK-SELECTOR.

concern I To all whom it may I, ALBERT M. BULLARD,

Be. it known that citizen of the United States, residing at New York, in the county of New York and State of New York, have invented a certain new and useful Improvement in Automatic Trunk-Selectors, of which the following isa full, clear, concise, and exact description.

My invention relates to a telephone exchange system, and more particularly to a system of trunk selection by an automatic selector, my object being to provide means for causing said selector to test said trunk lines by groups. 1

Generally speaking, my invention contemplates a number of trunks or other lines extending to terminals upon a selector, and divided into groups, means being provided for automatically ascertaining the busy condition of an entire group at one time, instead of testing each trunk'in turn. The lines being divided into groups, in case all the trunk lines in the first group are busy, thecontact arm of the selector will pass directly over or by said busy group and test the next group and each succeeding busy group until one is found containing one or more idle lines. Thereupon, the selector proceeds to test each separate line in the groupuntil the first free line is reached.

More specifically, the contact arm of the selector may be arranged to have two movements, one a long step for passing from group to group of terminals, and the other a short step for passing from terminal to terminal in a group containing one or more idle lines. In case the first group of trunks contains at least one free trunk, the means for giving the arm short steps are rendered operative to step the arm from terminal to terminal of the group until said idle line is reached, a trailing brush testing for the free trun'k as it goes along; but if all the trunks of the first group were busy, the mechanism for giving the arm a long step would have been brought into service, and

the arm stepped directly into the next group, and so on until a" group is found containing at least one idle trunk, when the long-step mechanism is cut off and the shortstep means brought into play to advance Specification of Letters Patent.

Patented July 18, 1916.

0, 1906. Serial No. 333,875/

the arm to the terminal of the free trunk line in the group.

With the above arrangeme t, a consider able saving in time is obtained in testing the lines, due to the ability to greatly curtail the total number of selective steps that mustbe taken before arriving at the first idle line. The system readily lends itself to different arrangements of groups, afiording great flexibility, and may be applied to any desired type of selector.

I will describe my invention by reference to the accompanying drawing, which is a diagram illustrating a trunking system embodying my invention, for the appended claims a statement of the parts, improvements and combination which I consider novel with me.

In the drawing is shown a trunk selector 1 of the rotary type, on the face whereof may be provided terminals for 100 trunk lines divided into groups of ten lines each, each line being multipled through a number of selectors, as shown. I have shown but one group of trunk-lines leading to terminals upon the trunk selector 1. The terminals are arranged in three concentric circles about the axis of the arm, the terminals 2 constituting the test terminals of the lines, while the inner terminals 3, 4 are, the line terminals. I have shown local conductors 2 extending from the local contacts 2 upon selector 1 to local terminals 2" of other selectors. A rotary contact arm 5 is mounted to swing over said terminals, said arm carrying insulated line brushes 6, 7, a local brush 8 and a special test brush 9.

Each group of terminals is provided with a test segment or plate 10 adapted to be en.- gaged by test brush 9, while the arm is one short step away from the first terminals in the group. The arm 5 is arranged to have two movements, a long step over one group reserving, however,

to the next, and a short step, from terminal 59 ratchet 16 is provided for advancing said responding in number to the number of 5 groups of trunk lines and terminals,in the 7 present case, 10. Ratchet 16'is provided with a stepping pawl 17 adapted to be operated bymagnet 18. The line brushes 6'7 of the arm 5 are shown normally connected by. conductors 1920 with the line termlnals 21, 22, respectively, of a selector 23, the local brushes 29, 29 and 29 and one set of terminals 27, 22 and 21 of the selector, only, being shown, said conductors 1920 including the armatures 2425 and their back'contacts respectively of a" relay 26. The local terminal 27 of selector 23 is connected with conductor 28 which leads to earth through retaining magnet 13. The local brush 29 of the selector 23 is connected with a conductor 30 which leads to earth through battery 31.

' The retaining magnet 13 is provided with an armature 32 which, when retracted, engages retaining pawl 12 to maintain the 25 same out of engagement with ratchet 11.

Said armature also when retracted opens contacts 33, 34 Contact 33 is connected by conductor 35 with the free pole of grounded battery 36, while contact 34 is connected 30 with conductor 37 which leads to armature 38 of relay 40, through contactsprings 43, 44, which are separated by arm 5 while away from normal position, and thence to earth through the winding of relay 26.

The armature 45 of relay 26 is connected to earth by conductor 46, and the front contact of said armature is connected with a conductor 47 which leads through the armature 39 and its back contact of relay I 40 through short-step magnet 15 to pulsator 48 and grounded battery 49. From the local brush 8, a conductor 50 extends through the armature 42 and back contact of relay 40 to armature 51 of relay26, whose front contact is connected with the portion of conductor 37 leading to earth through relay 26. Thus while the arm is moving in short steps over the terminals of a group, when the brush engages the local contact of a busy line, it will find current from grounded battery 52 of a selector already connected with such line, and a circuit will be maintained for relay 26, permitting the arm to be stepped to the next terminal. From the 55 special test brush 9, which engages the testplate of a group one short step from the first,

row of terminals in said group and remains in contact therewith until after the arm passes over said group, a conductor 53 leads normally through contact springs 54, 55,

separated by arm 5 while away from normal position to armature 41 of relay 40, through winding of relay 40 to armature 39 of said relay, which is connected to earth by conductor 47 when armature 45 of relay 26 is attracted. From the front contact of armature 39, a conductor 56 leads through longstep magnet 18 to conductor 47, between ture 38 of relay 40 is connected by conductor 58 with conductor 37, so that when armature 38 is attracted a circuit is completed for relay 26 independent of the springs 43-44. Thus if brush 9 finds current on the test plate 10,.a circuit for relay 40 is completed, which brings the long-step magnet 18 into circuit, and advances the arm to the next group. From the test plate of each group of terminals a conductor 59 leads through a series of ten pairs of normally open contacts 60, 61, to the free pole of grounded battery 62. Each trunk line of the group is provided with a pair of said contacts which are closed when such line is made busy-at some other selector. Thus from each local line 2 of the trunk lines a conductor 63 leads through the winding of a relay 64 to earth, said relay when energized closing the pair of contacts 60, 61 associated with its trunk line. Thus when all of said pairs of contacts are closed, current from battery 62 will be applied to test plate 10 of the group of terminals upon selector 1. The battery 52, as already stated, is connected with the local contact of any selector making connection with any of said trunk lines, and serves to energize the relay 64 associated with said line.

Operation.

Free group-testing.1 will now trace the operation of searching for a non-busy trunk in a free group, and will assume that the first group contains an idle line, in which event there would be no potentialat segment 10. The selector 23 having made connection with the line leading to trunk selector 1, a circuit 30, 28 will be completed at the local contacts of selector 23 for retaining magnet 13. The armature 32 of said magnet in operating applies retaining pawl 12 to ratchet 11, and closes contacts 33, 34, whereupon a circuit is completed from the free pole of grounded battery 36 by way of conductors 35, 37, contacts 43, 44, relay 26, to earth. The armature 45 of relay 26 is thereupon attracted and completes a circuit from the free pole of grounded battery 49, through pulsator 48, conductor 47, short-step magnet 15, armature 39 and its back contact of relay 40, conductor 46 to earth. The magnet 15 thereupon operates pawl 14 to advance the arm 5 to the termi- 43, 44 and 54-55, the springs the arrgature 51 of said magnet when attracted y the energization of said relay as 'before described, connected said relay 26 in a ground branch from, the local brush 8 of the arm 5, said branch extending by way of conductor 50, armature 42 and back contact group of ten lines.

of relay 40, armature 51 of front contact to conductor to earth through relay 26. Now if the first trunk line of the group is busy, the local terminalv 2 will be connected with the grounded battery 52 of the selector using such trunkline, and relay 26 will remain energized and maintain the circuit 47, 46 of the short-step magnet arm 5 will be advanced to the terminals of the second trunk line. If the second trunk of the group is busy, the arm 5 continues its advance in short steps from terminals to terminals until brush 8 reaches a nonbusy or ungrounded trunk, for example, trunk 6, whereupon the circuit of relay 26 is broken, and its armature retracted, breaking at armature 45 the circuit of stepping magnet 15, and restoring at armatures 24, 25 the line or talking circuit between selectors 23, 1.

Busy group testing.-As before stated, the trunk lines are multipled through several selectors. The drawing shows only the multipling of the test terminals of one As shown in dotted lines, a local terminal'of each line is con- 37, and thence mooted with a test brush of a selector which is connected with the free pole of grounded battery 52. Thus circuits would be completed over conductors 2, 63, for the ten relays 64, which would close the pairs of contacts 60, 61, thereby connecting the free pole of battery 62 with the test plate 10. Now when relay 26 is energized, as before described, battery 62 is connected with test plate 10, and current flows through test brush 9, conductor 53, springs 54, 55, relay 40, conductor 47, to earth through the armature 45 and front contact of relay 26; andalso circuit-.47, 46, of the short-step magnet is completed, but relay 40 instantly breaks this circuit, thus preventing said magnet from operating. Relay 40 is now energized, and by attracting its armatures brings about the following circuit changes: Armature 41 completes at its front contact a circuit for the relay 40, independent of the springs 54, 55,-this circuit being traced from the brush 9, over wire 53, wire 57, front contact of armature 41, winding of relay 40, wire 65, front contact of" armature 45, relay 26, through wire 46 to earth. The arma- 54, 55 when through contact '33, wire 37, armature 38 and its front contact,

relay 26, and its 15, whereupon the ture 38 completes a circuit for relay 26, which may be traced from battery '36 through the winding of relay .26Hto earth. ThlS circuit is independent ofthe springs 43 and 44. Armature 42, in leaving its back contact breaks the previously traced circuit from the local brush 8', through wire 50 and front contact of armature 5 1 of relay 26 to earth. Armature 39, at its back contact,

breaks. the circuit of the short step magnet 15', and at its front contact makes a on:

cuit for the long step magnet 18, which may be tracedfrom the grounded battery 49 and pulsator 48, through wire 47, long step magnet 18, wire 56, front contactof .armature 39, wire 65, front contact of armature 45 of relay 26, through wire 46 to earth. The magnet 18 thereupon operates pawl 17 and ratchet 16 to advance said arm 5 in a single step over the group, leaving said arm at trunk 9 one short step from the first line terminals in the second group, with the brush 9 on the segment 10 of such second group, and so on from group to group until the brush 9 finds a segment 10 without current thereon, which, of course, would occur when a group is reached having one or more idle lines therein. Assume that line 6, of said group were free, the relay 64 of such line would be inert and the continuity of the conductor 59 connecting the segment of such group would be broken, leaving said segment dead. Relay 40 would therefore be rendered inert and the circuit of the long-step magnet would be broken, while' the circuit of the short-step magnet 15 would be completed, as described above, to advance the arm in short steps until the terminals of the first idle line, No. 6, were reached. It will be noted that during the long steps of the arm, the circuit of local brush 8 is broken at the armature 42 and back contact of relay 40, thus keeping said brush dead while the arm is passing over a busy group. Similarly, brushes 6, 7, are dead at open back contacts of armatures 24, 25, of relay 26, until a free line is found. Should aline in a group become free as the arm was passing the group in long steps, battery 62 would become disconnected from the segment 10, causing relay 40 to release.- This would instantly stop the arm and would complete the circuit of the short-step magnet 15, thus causing the arm to progress in short steps until an idle line is found, either in that group or a. group beyond.

Having thus described my invention what wire 58," wire 37,-

battery 62 with I claim as new and desire to secure by Letsaid arm for testing "said terminals individually and by groups.

2. ,In a selector, groups of trunk line terminals arranged in a single plate, an-arm adapted to 'm'ovekover saidterminals in a g Y .vidually. andfby groups.

' 3.'In a selector, groups of trunk line terminals, group terminals individual to each group,'an d test brushes adapted to simultaneously wipe over said line and group terminals to test such trunk lines by groups and individually.

4. The combination with groups of trunk line terminals, of a contact arm, means for stepping said arm past busy groups in long steps, and means for stepping said arm In short steps over a group containing an idle trunk line until said idle line is reached.

5. Thecombination' with .a selector carrying groups of trunk lineterminals, of a contact arm therefor adapted to test said trunk lines by groups, means, actuated in case all the trunk lines terminating in a tested group are busy, for advancing said arm in a single long step to the next group, and so on until a group containing an idle trunk line is found, and means, operated when said last-mentioned group is reached for advancing said arm in short steps over the terminals of said group to the terminal of the first idle trunk line therein.

6. The combination with aselector carrying groups of trunk terminals, of a contact arm therefor, a relay responsive to the busy condition of all lines in a group, a

magnet operated by said relay when responsive, adapted to advance said arm in a long step over said group to the next group, and a magnet operative when said relay is unresponsive, adapted to step said arm in short steps to the terminal of the first idle trunk line of said group.

7. The combination with a selector carrying groups of trunk terminals, of a con tact arm therefor, a relay, a circuit therefor completed as said arm tests a group all of whose lines are busy, said circuit remaining open in case one or more lines in said group are busy, a magnet adapted to advance said arm in a long step over said group to the next group, a circuit for said magnet completed by said relay when energized, a magnet adapted toradvance said arm in short steps to the terminal of an idle line in said group, and a circuit completed for said magnet in case said relay remains inert.

8. The combination with groups of trunk lines, of a selector carrying a group of terminals for each group of trunk lines, a test contact for each group of terminals, a source of busy current associated with each group of lines, a conductor adapted to connect said source with said contact, a series of pairs of normally open contacts in said conductor,

one for each trunk-line in said group, and means operatlve as eachllne is made busy for closing its pair of contacts in the series;

whereby .when all of the trunk-lines in a group are busy said busy current is applied to the test contact.

9. The, combination with groups of trunk lines, of a trunk selector carrying groups of terminals for said groups of trunk lines, said lines being multipled to terminals upon other selectors, a test plate for each group of terminals, a source of busy current associated with each group of lines, a conductor adapted to connect said sourcewith said plate, a series of pairs of normally open contacts in said conductors, one for each trunk line in said group, a relay associated with each trunk line, and a circuit therefor completed when said trunk line is in use at one of said other selectors, said relay being adapted to close said contacts of said line,

whereby, when all the trunk lines in a group are busy, said busy current is applied to said test-plate.

10. The combination withgroups of trunk lines, of a selector carrying terminals for said trunk lines arranged in corresponding groups, a test plate for each group of trunk line terminals, a source of grounded current associated with each group of lines, a conductor adapted to connect said source with said plate, a series of pairs of normally open contacts in said conductor, one for each trunk line in said group, means operated as each line is made busy for closing its pair of said contacts, a contact arm for said selector carrying a test brush adapted to engage said plates, a grounded conductor connected with said brush, a relay in said conductor responsive in case said brush finds current on a test plate, a magnet adapted to step said arm over a busy group of terminals to the test plate of the next group, and a circuit therefor completed by said relay when responsive.

11. The combination with groups of trunk lines, of a selector carrying terminals for said trunk lines arranged in corresponding groups, a test plate for each group of trunk line terminals, a source of grounded current associated with each group of lines, a conductor adapted to connect said source with said plate, a series of pairs of normally open contacts in said conductor, one for each trunk line in said group, means operated as each line is made busy for closing its pair 1,1e1,1s2 I a to the test plate of the next group, a circuit In witness whereof, I, hereunto subscribe therefor completed alay sail relay wheln remy name this 3rd day of August A. D., 1906. sponsive, a, magnet apte to step sai arm from terminal to terminal in a. group to the V ALBERT terminal of an idle line therein, and a. circuit Witnessesf including a pulsator closed by said relay J 01m G. Ronnnrs,

when unresponsive. CLARENCE A. Comm; 

